Cognitive tests: interpretation for neurotoxicity? (Workshop summary).

The appropriate use and interpretation of cognitive tests presents important challenges to the toxicologist and to the risk assessor. For example, intelligence cannot be measured directly; rather intelligence is quantified indirectly by scoring responses (i.e., behaviors) to specific situations (problems). This workshop, "Cognitive Tests: Interpretation for Neurotoxicity?" provided an overview on the types of cognitive tests available and described approaches by which the validity of such tests can be assessed. Unlike many tools available to the toxicologist, cognitive tests have a particular advantage. Being noninvasive and species-neutral, the same test can be performed in different mammalian species. This enhances one's ability to assess the validity of test results. Criteria for test validity include comparable responses across species as well as similar disruption by the same neurotoxicant across species. Test batteries, such as the Operant Test Battery, have indicated remarkable similarity between monkeys and children with respect to performance of certain tasks involving, for example, short-term memory. Still, there is a need for caution in interpretation of such tests. In particular, cognitive tests, especially when performed in humans, are subject to confounding by a range of factors, including age, gender, and, in particular, education. Moreover, the ability of such tests to reflect intelligence must be considered. Certain aspects of intelligence, such as the ability to plan or carry out specific tasks, are not well reflected by many of the standard tests of cognition. Nonetheless, although still under development, cognitive tests do hold promise for reliably predicting neurotoxicity in humans.